Alter table modify enum in Knex js for Postgresql gives error

Question

I am using knex js and postgresql database. I have used a migration file to create a table knex migrate:make create_car_table. In this I have added a column fuel_ty

Answer 1

You first need to drop the existing constraint, and create a new one with the new values. The code sample below should help.

exports.up = function(knex, Promise) {
  return knex.schema.raw(`
    ALTER TABLE "car" DROP CONSTRAINT "car_fuel_type_check";
    ALTER TABLE "car" ADD CONSTRAINT "car_fuel_type_check" CHECK (fuel_type IN ('HYBRID'::text, 'ELECTRIC'::text, 'PETROL'::text, 'DIESEL'::text))
  `);
};

// The reverse migration is similar
exports.down = function(knex, Promise) {
  return knex.schema.raw(`
    ALTER TABLE "car" DROP CONSTRAINT "car_fuel_type_check";
    ALTER TABLE "car" ADD CONSTRAINT "car_fuel_type_check" CHECK (fuel_type IN ('PETROL'::text, 'DIESEL'::text, 'CNG'::text));
  `);
};

I'm assuming your constraint name is car_fuel_type_check. If not, you should replace car_fuel_type_check with your constraint name.

Answer 2

Alter column does not work for enum types in knex 0.13.0.

Also enums are implemented as check constraints, so to change it you need to recreate the.

Something like this:

exports.up = function(knex, Promise) {
  return knex.schema.raw(`
    ALTER TABLE "car"
    DROP CONSTRAINT "car_fuel_type_check",
    ADD CONSTRAINT "car_fuel_type_check" 
    CHECK (fuel_type IN ('HYBRID', 'ELECTRIC', 'PETROL', 'DIESEL'))
  `);
};

exports.down = function(knex, Promise) { ... };

You might need to check your constraint name that was originally generated by knex from the DB.

Currently knex.schema.raw is the only way to modify enums.